A search and rescue operation for a youth football team, who authorities believe are trapped in a flooded cave, has temporarily been halted in northern Thailand amid rising water levels and heavy rain.

The 12 boys aged 11-16, and their 25-year-old coach, who reportedly entered the Tham Luang Nang Non cave in Chiang Rai province on Saturday afternoon, are believed to be alive, officials said on Monday.

"We have found traces of the children's footprints and we believe that they are still alive," said Passakorn Boonyalak, deputy governor of Chiang Rai province, 1,000 kilometres north of Bangkok.

"The rescue team has also prepared food and water for the group," he told reporters on Monday.

The Moo Pa Academy team's belongings, including bicycles, backpacks and football cleats, have been found just outside the entrance of the flooded cave complex in Chiang Rai's Mae Sai district, where they had gone for a sightseeing trip, Thai Public Broadcasting Service reported.

The rising water obstructed the rescue operation on Monday, as Royal Thai Navy SEAL divers, struggled to move farther into the cave complex, which is thought to be about 6-8km long and contain some large chambers.

By Monday evening, officials made the call to temporarily pull out.

"We went in a few kilometres and were able to enter a second chamber behind the entrance," Lieutenant Naponwath Homsai, a SEAL team member, told AP news agency.

"In that chamber, there was an area where I saw shoes and bags left behind on the ground. We believe the students have gone further in."

He said they would wait for water pumps to be brought in which would hopefully help them access another passageway.

The SEAL team arrived at the site on Monday morning to begin their search after multiple local rescue teams could not make much progress.

'I still have hope'

Mothers and other relatives of the missing boys held a prayer session on Monday evening at the entrance to the cave, where there is a shrine with a statue of the Buddha.

They laid flowers and then some walked inside, where their cries could be heard echoing off the walls.

"My son, come on out! I am waiting for you here!" one woman cried. Another kneeled down near the bicycles and prayed, asking "Where is my child?"

Namhom Boonpiam, whose 13-year-old son Mongkol is among the missing, said she had been waiting at the entrance since Saturday night.

"I haven't slept and I hope that all of them can come out, all safe and sound," she told AP news agency. "My son is a strong boy. I still have hope."

Despite heavy rain and rising waters, officials believe that there are still safe spaces in the cave complex, Chiang Rai Deputy Governor Passakorn Bunyalak told a news conference.

"We're confident that the kids should still be in good condition," he said, noting that rescuers had seen nothing inside the cave to indicate otherwise.

Thailand is currently in the middle of a rainy season, which often causes floods in caves. (Aljazeera)

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